Compensating Method for Image Scanning, Image Scanning Apparatus and Image Processing System
A compensating method for image scanning measures original optical values corresponding to a plurality of scan lines in a frame using a plurality of channels. First, a reference channel is selected from the plurality of channels. Based on the differences between the actual exposure locations of the reference channel and other channels on the frame, corresponding weighting values are then generated for compensating the original optical values measured by other channels, thereby generating the correction optical values for other channels.
1. Field of the Invention
The present invention is related to a scanning method and related apparatuses, especially a scanning method and related apparatuses capable of compensating image quality.
2. Description of the Prior Art
A contact image sensor (CIS) is one kind of linear sensors, and is often used on devices such as scanners, fax machines, or multi functional printers, for scanning and transforming graphics or documents into digital image data, so that users can edit the image data through a computer, print through a printer, send to others via fax or e-mail, and share with others through Internet.
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Nevertheless, in reality, the CIS scanner forms an image by using the stepping motor to drive the sensor module, exposing the red, green, and blue channel line by line to receive reflection light signals. For instance, the first line exposures the red channel, the second line exposures the green channels, the third line exposures the blue channel, the fourth line exposures the red channel, and so on. Since the CIS scanner can only handle the reflection light of one single color during the same exposure duration, the red, green, and blue channels corresponding to the same scan line are measured on different positions.
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It is therefore a primary objective of the present invention to provide a compensating method for image scanning, an image scanning apparatus and an image processing system.
The present invention discloses an image scanning compensating method. The image scanning compensating method comprises moving an optic sensing module for sequentially scanning a frame and generating a plurality of scan lines, reading a first original optic value, a second original optic value, and a third original optic value corresponding to an N-th scan line of the plurality of scan lines through a first channel, a second channel, and a third channel of the optic sensing module, reading a fourth original optic value, a fifth original optic value, and a sixth original optic value corresponding to a (N+1)-th scan line of the plurality of scan lines through the first channel, the second channel, and the third channel of the optic sensing module, choosing a reference channel from the first channel to the third channel, adjusting the first original optic value to the third original optic value respectively for generating a first optic compensating signal to a third optic compensating signal according to differences of actual exposure location of the reference channel and actual exposure locations of the first channel to the third channel other than the reference channel when reading the N-th scan line, adjusting the fourth original optic value to the sixth original optic value respectively for generating a fourth optic compensating signal to a sixth optic compensating signal according to differences of actual exposure locations of the first channel to the third channel other than the reference channel when reading the (N+1)-th scan line and the actual exposure location of the reference channel when reading the N-th scan line, generating a first correction optic value corresponding to the first channel and the N-th scan line according to the first optic compensating signal and the fourth optic compensating signal, generating a second correction optic value corresponding to the second channel and the N-th scan line according to the second optic compensating signal and the fifth optic compensating signal, generating a third correction optic value corresponding to the third channel and the N-th scan line according to the third optic compensating signal and the sixth optic compensating signal, and outputting image signals corresponding to the N-th scan line according to the first correction optic value to the third correction optic value.
The present invention further discloses an image scanning apparatus capable of compensating images. The image scanning apparatus comprises an optic sensing module comprising a plurality of channels, for providing light sources for a frame, detecting a plurality of original optic values based on reflection of the frame, and converting the plurality of original optic values to a plurality of analog signals, an analog-to-digital converter for converting the plurality of analog signals to a plurality of digital signals, and a controller for adjusting the plurality of digital signals respectively according to differences of actual exposure locations of the plurality of channels on the frame.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
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The image processing system 300 in the present invention can calculate the correction optic values through a main program stored in the controller 130 based on original optic values, or generate the correction optic values through digital signal processing (DSP) circuits in the controller 130. Meanwhile, the image processing system 300 can also calculate the correction optic values through a driving program in the host 200.
In summary, the present invention selects a reference channel from a plurality of channels, and generates corresponding weighting values based on differences of the actual exposure locations of the reference channel and other channels. Then, according to the weighting values, the present invention can correct the original optic values of the channels, so as to generate the correction optic values. Therefore, the present invention can compensate color distortion caused by differences of the actual exposure locations of different channels, and improve the scanning quality.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.
Claims
1. An image scanning compensating method comprising the following steps:
- (a) moving an optic sensing module for sequentially scanning a frame and generating a plurality of scan lines;
- (b) reading a first original optic value, a second original optic value, and a third original optic value corresponding to an N-th scan line of the plurality of scan lines through a first channel, a second channel, and a third channel of the optic sensing module;
- (c) reading a fourth original optic value, a fifth original optic value, and a sixth original optic value corresponding to a (N+1)-th scan line of the plurality of scan lines through the first channel, the second channel, and the third channel of the optic sensing module;
- (d) choosing a reference channel from the first channel to the third channel;
- (e) adjusting the first original optic value to the third original optic value respectively for generating a first optic compensating signal to a third optic compensating signal according to differences of actual exposure location of the reference channel and actual exposure locations of the first channel to the third channel other than the reference channel when reading the N-th scan line;
- (f) adjusting the fourth original optic value to the sixth original optic value respectively for generating a fourth optic compensating signal to a sixth optic compensating signal according to differences of actual exposure locations of the first channel to the third channel other than the reference channel when reading the (N+1)-th scan line and the actual exposure location of the reference channel when reading the N-th scan line;
- (g) generating a first correction optic value corresponding to the first channel and the N-th scan line according to the first optic compensating signal and the fourth optic compensating signal;
- (h) generating a second correction optic value corresponding to the second channel and the N-th scan line according to the second optic compensating signal and the fifth optic compensating signal;
- (i) generating a third correction optic value corresponding to the third channel and the N-th scan line according to the third optic compensating signal and the sixth optic compensating signal; and
- (j) outputting image signals corresponding to the N-th scan line according to the first correction optic value to the third correction optic value.
2. The scanning method of claim 1, wherein the optic sensing module is a contact image sensor.
3. The scanning method of claim 1, wherein the first channel, the second channel and the third channel are a red channel, a green channel, and a blue channel of the optic sensing module, respectively.
4. The scanning method of claim 3 further comprising:
- sending a red light source to the frame through the red channel;
- sending a green light source to the frame through the green channel; and
- sending a blue light source to the frame through the blue channel.
5. The scanning method of claim 4 further comprising:
- measuring reflection of the red light source from the frame for generating the first original optic value and the fourth original optic value;
- measuring reflection of the green light source from the frame for generating the second original optic value and the sixth original optic value; and
- measuring reflection of the blue light source from the frame for generating the third original optic value and the sixth original optic value.
6. The scanning method of claim 3, wherein step (d) is choosing the red channel as the reference channel, and the first original optic value and the fourth original optic value are equal to the first correction optic value and the fourth correction optic value respectively.
7. The scanning method of claim 6 further comprising:
- generating a first weighting value according to a difference between actual exposure locations of the green channel and the red channel when reading the N-th scan line;
- generating a second weighting value according to a difference between actual exposure locations of the green channel and the red channel when reading the (N+1)-th scan line;
- multiplying the second original optic value by the first weighting value for generating the second optic compensating signal; and
- multiplying the fifth original optic value by the second weighting value for generating the fifth optic compensating signal.
8. The scanning method of claim 6 further comprising:
- generating a first weighting value according to a difference between actual exposure locations of the blue channel and the red channel when reading the N-th scan line;
- generating a second weighting value according to a difference between actual exposure locations of the blue channel and the red channel when reading the (N+1)-th scan line;
- multiplying the third original optic value by the first weighting value for generating the third optic compensating signal; and
- multiplying the sixth original optic value by the second weighting value for generating the sixth optic compensating signal.
9. The scanning method of claim 3, wherein step (d) is choosing the green channel as the reference channel, and the second original optic value and the fifth original optic value are equal to the second correction optic value and the fifth correction optic value respectively.
10. The scanning method of claim 9 further comprising:
- generating a first weighting value according to the difference between actual exposure locations of the red and the green channel when reading the N-th scan line;
- generating a second weighting value according to the difference between actual exposure locations of the red and the green channel when reading the (N+1)-th scan line;
- multiplying the first original optic value by the first weighting value for generating the first optic compensating signal; and
- multiplying the fourth original optic value by the second weighting value for generating the fourth optic compensating signal.
11. The scanning method of claim 9 further comprising:
- generating a first weighting value according to the difference between actual exposure locations of the blue and the green channel when reading the N-th scan line;
- generating a second weighting value according to the difference between actual exposure locations of the blue and the green channel when reading the (N+1)-th scan line;
- multiplying the third original optic value by the first weighting value for generating the third optic compensating signal; and
- multiplying the sixth original optic value by the second weighting value for generating the sixth optic compensating signal.
12. The scanning method of claim 3, wherein step (d) is choosing the blue channel as the reference channel, and the third original optic value and the sixth original optic value are equal to the third correction optic value and the sixth correction optic value respectively.
13. The scanning method of claim 12 further comprising:
- generating a first weighting value according to the difference between actual exposure locations of the red and the blue channel when reading the N-th scan line;
- generating a second weighting value according to the difference between actual exposure locations of the red and the blue channel when reading the (N+1)-th scan line;
- multiplying the first original optic value by the first weighting value for generating the first optic compensating signal; and
- multiplying the fourth original optic value by the second weighting value for generating the fourth optic compensating signal.
14. The scanning method of claim 12 further comprising:
- generating a first weighting value according to the difference between actual exposure locations of the green and the blue channel when reading the N-th scan line;
- generating a second weighting value according to the difference between actual exposure locations of the green and the blue channel when reading the (N+1)-th scan line;
- multiplying the second original optic value by the first weighting value for generating the second optic compensating signal; and
- multiplying the fifth original optic value by the second weighting value for generating the fifth optic compensating signal.
15. An image scanning apparatus capable of compensating images comprising:
- an optic sensing module comprising a plurality of channels, for providing light sources for a frame, detecting a plurality of original optic values based on reflection of the frame, and converting the plurality of original optic values to a plurality of analog signals;
- an analog-to-digital converter for converting the plurality of analog signals to a plurality of digital signals; and
- a controller for adjusting the plurality of digital signals respectively according to differences of actual exposure locations of the plurality of channels on the frame.
16. The image scanning apparatus of claim 15, wherein the optic sensing module is a contact image sensor (CIS).
17. The image scanning apparatus of claim 15, wherein the analog-to-digital converter comprises an analog front end (AFE) circuit.
18. The image scanning apparatus of claim 15 further comprising a host having a driving program for adjusting the plurality of digital signals according to the differences of the actual exposure locations of the plurality of channels on the frame.
Type: Application
Filed: Oct 16, 2007
Publication Date: Aug 28, 2008
Inventor: Sheng-Min Wang (Keelung City)
Application Number: 11/872,721
International Classification: H04N 1/04 (20060101);